Tropical landscapes with fragmented habitats and increasing levels of human use still harbor hundreds of globally threatened species that cannot survive anywhere else (Meyers et al. 2000). Ecosystem services in natural areas are also especially important for provisioning and protecting impoverished people, and have been undermined through deforestation, land degradation, and pollution. As natural assets are depleted, poverty reduction becomes more costly, with less protein from hunting and fishing and increased incidences of flooding and waterborne diseases affecting the most vulnerable communities (Millennium Assessment, 2005). Many natural areas are reaching their limits in terms of their longstanding capacity to serve as a safety net for the rural poor during periods of economic and political transformation (Pattanayak & Sills, 2001).

Considerable deforestation in tropical developing countries occurs as an unintended consequence of rural development policies that enable both rich and poor to degrade the environment as part of a process of building individual assets, only to leave the remaining landscapes less capable of supporting those who remain (Chomitz, 2006). Neither government agencies nor forest dwellers’ regimes have adequate governance tools or resources to manage the vastly increased incentives for short-term profiteering in frontier regions that are experiencing agricultural expansion, road construction, and in-migration. The two papers in this forum describe how human behavioral response to changing environmental conditions at the forest frontier sets up further unintended consequences that can be understood with research. Both papers also highlight that these insights will need to be matched by a science that is only in its infancy: the ability to evaluate the causal effectiveness of policy responses (Ferraro & Pattanayak, 2006).

Naughton-Treves and colleagues find that in Ecuador and Peru protected areas occupy twice the area that they did a quarter century ago, but with increasingly complex arrangements to accommodate the thousands of people living inside their boundaries. The expansion of protected areas was often justified by the need to safeguard rare and vulnerable ecosystems, despite higher human population densities. A number of these expanded parks, some established with protections consistent with IUCN categories I or II, now include significant human populations, and this has created management regimes that are incongruous with the actual patterns of use.

In these situations, park managers have responded in some cases by adjusting the boundaries to exclude communities that rejected the enforcement of regulations, while in other cases they have worked to establish internal zoning for community use of resources. Internal zoning often has tenuous legitimacy and lacks mechanisms for observing, enforcing, or adjudicating related rules. Though the processes for making internal zones have become more participatory and transparent, the legal status of the parks means that property rights over extractive uses within the established zones remains uncertain.

Zoning as a response to the changing environmental conditions of expansive parks creates contradictory incentives and sets the stage for future conflict. Extensive areas cleared of forest within the protected areas of Indonesia , for example, inhibit agricultural use because their legal status impedes access to credit (Fay & Michon, 2005). The removal of protected status, in contrast, creates perverse incentives for further speculation in the conversion of public or communal lands. The robustness of internal zoning for parks and extractive reserves usually depends on the opportunity cost of more intensive uses and the strength of indigenous governance institutions. In some cases, growing access to markets and declining social cohesion spurred by external mining, forestry, or agricultural interests overwhelms internal zoning rules (Pinto da Silva, 2004). In other places, remoteness, community legal usage rights, and indigenous institutions are factors that can shore up the longevity of internal zoning rules (Nepstad et al. 2006).

This article by the group led by Naughton-Treves helps us to understand how the goal of slowing forest conversion, through the expansion of protected areas, and the postponement of legal usage rights inside them has created conditions for a human behavioral response—namely zoning—that will require a further evolution in the management institutions operating in protected areas. The authors recommend approaches providing formal contractual agreements between park authorities and resident communities in the form of co-management or compensated use-restrictions. Soon, park-management agencies may have financial mechanisms allowing them to pay communities for the carbon-storage value of avoided deforestation. However, the effectiveness of such institutions at reconciling forest-conversion control with economic opportunities for the mostly poor communities remains uncertain. Are park managers more effective implementers of co-management contracts, or are local governments, all other factors being equal? Greater clarity about the nature of the sustainability problem is necessary but not sufficient to allow prescription of policy responses likely to be more effective Understanding effectiveness will require tests of these instruments, controlling for varying market access, under different economic returns for logging, hunting, mining, and agricultural conversion.

In the same frontier regions, Pattanayak and his colleagues show that environmental change is a probable precursor to human behavior that will have consequential, but poorly understood, human-health effects. Degraded natural environments, with stagnant water pools, higher acidity, increased edge environments of patchy secondary growth, and greater in-migration are all likely to be linked to a resurgence of malaria, compounded by linked cascading effects of climate change and human interaction with sensitive environments. Recent scientific studies have identified independent causal links between road construction, changed human behavior, and malaria in Peru (Vittor et al. 2006) and diarrheal disease in Ecuador (Eisenberg et al. 2006).

The proposed research agenda on deforestation and human health articulates one of the chief priorities emerging from the Millennium Ecosystem Assessment:

At present, most ecosystem services are not marketed. The resulting lack of information about prices that reflect social value is an impediment to design and implementation of economic policy instruments. The gap is particularly acute for “regulating services,” such as disease and flood regulation and climate control, which are rarely priced, yet have strong effects (Carpenter et al. 2006).

Yet in the remote areas of the rural tropics, the road-development projects that these two papers contend are causally linked with greater in-migration pressure on parks and risks to human health, are usually popular with local populations. Road development is both an endogenous response to forest clearing and agricultural intensification, as well as an exogenous cause of it (Reis & Weinhold, 2004). Both theory and empirical evidence give reason to believe that some road development could improve market access for areas of intensive production, decreasing pressure on forests and bringing rural people access to health services. However, design principles for poverty-reducing roads and effective frontier-governance institutions remain almost entirely in the realm of speculative policy debate. Even as natural experiments proliferate regarding innovation in road building and frontier governance, they have not been pursued using research methodologies that adequately compare outcomes while controlling for confounding causal factors.

The science on human-environment dynamics at the forest edge continues to lag behind the emergence of new drivers of land-use change, such as the production of biofuels. The rationale for investment in controlled policy experiments can seem fragile compared to the need for direct action to prevent irreversible environmental damage. The two articles that comprise this forum implicitly caution, however, that the behavioral response to underachieving conservation action might be to reduce support for this action from its ostensible beneficiaries. This is a recipe for a continuing policy lag that delays even further the comprehensive incorporation of the total cost of biodiversity and ecosystem service loss in the prices of goods (e.g., soybeans, minerals, timber, bushmeat) that are produced at the forest edge.

The prevailing knowledge gaps on the monetized value of services that would allow for them to be incorporated in prices and help to pay for maintaining parks and controlling emergent diseases are not even the most glaring problem. The information deficiency is even greater regarding the costs of constructing the policy institutions that might implement common property regimes or economic instruments in different contexts. These institutions are unlikely to evolve out of political demands for an unrealized public good (Hoff & Stiglitz, 2001). It will be necessary to induce policy experiments and to take advantage of these opportunities to incorporate the scientific evaluation of policy effectiveness for the institutions that are developed.

Scientific insights about the places where the greatest environmental costs (and human welfare losses) might be avoided has too frequently been misperceived as knowledge about which policy interventions are effective in the extremely varied contexts where these losses can occur. This forum demonstrates the behavioral consequences that can occur when protected areas are expanded to slow deforestation and highlights a need to better understand the behavioral changes that deforestation, infrastructure development, and malaria emergence prompt in tropical areas. Facilitation of this awareness will require the integration of rigorous social and ecological science in an interdisciplinary context. This work should be aimed at understanding the opportunity costs of economic drivers, such as soybean expansion, logging, mining, hunting, and wildlife trade, in order to scale the countervailing incentives that are incorporated into common property institutions or economic instruments. To get ahead of the curve of worsening environmental degradation and the poverty traps that occur at the forest edge requires special attention to the scientific evaluation of policies that create incentives for environmental stewardship in the varied contexts of the tropical forest frontier.